Sewing machines



June 1959 T. A. KESTELL ET AL 2,888,892

SEWING MACHINES F iled Oct. 12, 1956 3 Sheets-Sheet l Inven tors ThomasA.Kesfel[ Raymond Snap Filed Opt. 12, 1956 June 9 v T. AfREsTELL EVTAL2,388,892

SEWING MACHINES v 3 Sheets-Sheet 2 3a I c. 26 w Z [0 Inventors 24 ThomasA. KeszelZ.

June 2, 1959 T. A. KEST ELL ET AL SEWING MACHINES 3 Sheets-Sheet 5 FiledOct. 12, 1956 fnven tors Thomas fl. Kesfell Paymona Snape United StatesPatent SEWING MACHINES Thomas Aubrey Kestell and Raymond Shape,Leicester,

England, assignors to United Shoe Machinery Corporation, Boston, Mass.,a corporation of New Jersey Application October 12 1956, Serial No.615,666

Claims priority, application Great Britain November 10, 1955 Claims.(Cl. 112-38) The present invention relates to lockstitch shoe-sewingmachines, and more particularly to improvements in a shoe outsolestitcher of the type disclosed in United States Letters Patent No.2,056,670, granted October6, 1936, on application of J. 'Gouldbourn etal.

In the machine of the Gouldbourn et al. patent a lockstitch seam isformed by employing a locking thread supply containing case mountedwithin a needle thread loop taker, which carries each loop of needlethread about the thread case, after which the needle loop is contractedagainst the locking thread and the interlocked needle and lockingthreads are drawn into the work by a take-up. Heretofore, it has been aproblem to control uniformly the action of each needle loop in drawingthe locking thread toward and into engagement with the work, the lockingthread being subjected to non-uniform action, including varyingfrictional tension as it is drawn from its supply in the thread casetoward the work.

Another cause for lack of uniform action of the locking thread in beingdrawn by the needle loop into the work arises from an inability to causeinitial contraction of the needle loop against the locking thread withcertainty at the same relative point along the length of the lockingthread running between the thread case and the work. Due to uncertaintyin the point at which the needle loop is initially contracted againstthe locking thread, more or less locking thread may be drawn into thework as each stitch is set, in spite of the provision of extremelyeflicient needle thread measuring mechanisms. The problem is complicatedfurther as a result of ineffective tension control on the lockingthread, both in the action of frictional tension devices on the lockingthread as it leaves the thread case and also from varying effects ofinertia in the locking thread supply, such as is met in rotating asupply reel with varying amounts of thread thereon. Consequently,irregular delivery of locking thread frequently occurs as each needleloop contracts against it, rotating the locking thread supplyintermittently at relatively high speed, a characteristic difiicultyencountered in most machines of the type referred to.

It is an object of the present invention to improve the uniformity withwhich a lockstitch shoe outsole stitcher, of the type referred to, formsand sets each stitch of a seam and avoids the difficulties met usuallyin this type of sewing machine during attempts to control the lockingthread, in spite of any uncertainty in point of engagement of the needleloop with the locking thread as the loop is contracted against it.

Other objects of the invention are to simplify and improve theconstruction and mode of operation of a shoe outsole stitching machineof the type referred to, and to enable the use of a compact andefficient design of thread controlling device mounted on the lockingthread supply containing case.

In prior attempts to attain objects of a nature similar to those aboveenumerated, a yieldable thread control arm-has been provided on alocking thread supply case,

ice

. 2 arranged to take up the looseness in the locking thread, but onaccount of the restricted space available the amount of thread capableof being payed out by said yielding arm is extremely limited. Theyielding force of the am also may vary substantially from one stitch toanother on account of unavoidable changes in thread. requirementsbetween successive stitches. Thus, the use: of a yielding arm aloneunder such conditions does not: necessarily insure uniformity ofstitching.

One feature of the present invention enabling improved. uniformity withwhich a lockstitch sewing machine is: capable of forming and settingstitches comprises theprovision in such machine of stitch-formingdevices of conventional form, including a hook needle, a loop taker forpassing loops of needle thread about a thread case, a take-up fordrawing each loop of needle thread fromthe thread case, and a yieldablecontrol member on thethread case, in which machine there also isprovided means for actuating the yieldable member positively in adirection opposite to that of its yielding movement to return ituniformly to a predetermined initial starting position. In this way fullbenefit is obtained within the restricted space available for the fullmovement of theyieldable member from its starting position to the end ofits thread paying out stroke during each stitch forming cycle.Presumably, the full paying out stroke of the yieldable member issuflicient to accommodate the maximum thread requirements for themachine. Preferably, the actuating means for the yieldable member is inthe form of a cam on the loop taker itself, there being no additionalmechanism interposed between the loop taker and the work, such as mightoffer inconvenience, either in manipulation of the work or in applyingor removing the supply of locking thread from the machine. Ashereinafter described, this feature of the invention is particularlybeneficial when employed in a machine having needle thread measuringmechanism, to provide a uniform tension on the locking thread regardlessof the irregularities in thread requirements, the full benefit of theneedle thread measuring mechanism being thus obtained.

Where no separate mechanism for measuring needle thread is employed, thefeatures of the present invention provide means not only for imparting auniform tension to the locking thread from one stitch to another, butalso for utilizing with success a uniform measurement of locking threadin an amount sufiicient for the formation of each stitch, the fullpaying out stroke of the yieldable member providing an amount equal tothe maximum ordinarily required for each stitch.

The action of the yieldable member, in accordance with a further featureof the invention, is rendered extremely accurate in measuring threadthrough the provision of lockingthread tensioning and clamping devices,including a conventional thread tension spring and a face on the cam foractuating the yieldable member to prevent withdrawal of locking threadfrom the supply bobbin during the short interval while each stitch isbeing set.

These and other features of the invention, hereinafter described andclaimed, will be apparent from the follow-' ing detailed specification,taken in connection with the accompanying drawings, in which:

Fig. 1 is a view in right hand side elevation showing a" front portionof the head of an outsole stitcher, embody},

Fig. 3 is a developed view of the cylindrical side wall of the lockingthread case shown in Fig. 2, illustrating the relationship of certain ofthe parts prior to a stitch setting- .operation in the machine;

Fig. 4 is a similar developed view showing the relationship of the sameparts while a stitch is being set;

Fig. 5 is a sectional view, looking from the front, on a somewhatreduced scale of the thread supply case shown in 'Fig. 2, including aloop taker surrounding the thread case;

Fig. 6 is a perspective view of a cam on the looptaker for actuating ayieldable thread control-ling member on the thread case;

Fig. 7 is a developed view similar to that illustrated inv Fig. 3 butshowing a modified form of the invention; and

Fig. 8 is an enlarged perspective view of a thread tensioning andclamping member shown in Fig. 7.

Except as hereinafter described, the machine illustrated in the drawingsis the same in construction, arrangement of parts and mode ofoperationas the machine disclosed in United States Letters Patent No. 2,049,369,granted July 28, 1936, upon application of J. Gouldbourn et al. and No.2,056,670 above identified. As in the machine of the patents, thestitch-forming devices comprise a curved hook needle 2, a curved awl 4,a needle looper 5, a hollow rotary shuttle or loop taker 6' for passingeach loop of needle thread 7 about a locking thread supply case 8 havinga cylindrical side wall 9 and an end wall'10, a main take-up 11, aneedle thread measuring mechanism, including a swinging thread guidinglever 12, and a pair of needle thread locks 14 and 16. To feed the workpresented to the stitch-forming devices, there is provided a feedingwork support 18 and a work clamping presser foot 20, both mounted on ahorizontally swing-i ing carrier 21. The take-up acts to draw eachneedle loop from the thread case toward the work, to' contract the loopof needle thread against the locking thread and to pull the interlockedneedle and locking threads into the work with a stitch setting tension.

Within the thread case is mounted a bobbin 22 (see Fig. 5 on which asupply of locking thread 24- is wound, the locking thread being ledthrough an opening 26 (Fig. 3) in the cylindrical side wall of thethread case beneath a flat spring frictional tension device 28, actingto con trol withdrawal of locking thread. To hold the tension device inplace it is formed with a locking projection 29, fitting a keyholerecess in the thread case 8. From: the tension spring the thread passesthrough a guide eye 30 in a portion of the cylindrical wall of thethread case near its forward end, which" is left open for convenientinsertion and removal of supply bobbins. To prevent rotation of thethread case with the loop taker 6, thethread case along its front end isprovided with a pair of forwardly extending lugs 32, between which isloosely engaged a removable thread case retainer in the form of an arm34, the locking thread 24 issuing from the guide eye 30 and extendingtoward the work close to one side of the retainer arm 34.

As in the operation of the machine of the prior patents, a measuredamount of needle thread is provided for each stitch by the threadmeasuring lever 12 and the take-up acts to withdraw the needle threadthrough the lock 14, which is opened at the proper time, so that themeasured amount of needle thread is rendered available for the the workis held straight under rigid tension before initial engagement with theneedle loop, the needle loop will slide along the locking. thread whilein straight condition toward a position at its point of emergencefromthe previous stitch in the work. Thereaften-duringi con- 4 I tinnedcontraction of the needle loop the locking thread is deflected fromstraight tensioned condition and is drawn from the thread case, theneedle loop sliding along the deflected portion of the locking thread ina reverse direction away from the previous stitch until the deflectedlocking thread is pressed against the surface of the work by thecontraction of the needle loop against it. Continued tension of theneedle thread then causes additional locking thread to be drawn from thethread case into the work and the stitch to be set. However, if thelocking thread running between the guide eye 30 and the work isuntensioned and slack before the needle loop is contracted against it,the length of locking thread between the previously formed stitch andthe needle loop is greater before additional locking thread is drawnfrom the thread case than otherwise would be. The initial point ofinterlocking engagement between the threads will then be further awayfrom the point of emergence of the locking thread from the previousstitch and as a result less tension in the needle thread will berequired to deflectthe locking thread against the work. Accordingly,more locking thread will be drawn from the thread case and the finalpoint of interlocking engagement of the threads will be drawn moredeeply into the work when the stitch is set, than would occur when thelocking thread is held straight under rigid tension between the guideeye 30 and the work, in a manner to direct the contracting needle loopimmediately to the point of emergence of the locking thread from thework. For these reasons irregularities in formation and setting ofsuccessive stitches have resulted. As thus far described the machine issubstantially the same as disclosed in the prior patent, above referredto.

As in prior attempts to maintain the locking thread" under rigid tensionbetween the locking thread supply case and the work, the present machineis provided with a yieldable paying-off device for taking up the slacklocking thread running between the tension member 28 on the thread caseand the work. However, the space avai'h" able for the paying-0E deviceis so small that its movement is extremely limited and unless the fullmovement of the device is available for paying-off locking thread andfor maintaining it under yielding tension during the successive stitchesstill are frequent.

According to an important feature of the present invention, the fulllength of movement of the yieldable paying-oif device is obtained byproviding an actuatingmeans' therefor, operable positively in adirection opposite to that of the yielding movement of the yieldabledevice to return it unifonnly to an initial predetermined startingposition during each sewing cycle. As illustrated in Fig. 2, theyieldable paying-off device comprises an enlarged head 36, having athread guiding eye, on a substantially inentialess spring member 38formed of steel wire; The spring member 38 is wrapped about the threadcase cylindrical side wall through an extent of about of its peripheryand is anchored at one end 40 in a flange of the thread case. The head36 is situated in a transverse cutout section 41 of the cylindrical sidewall of the thread case and is thus able to move to a limited extentthrough machine is capable of successful operation. The locking threadin the bight is thereafter available for movement yieldingly toward thework as a stitch being. formed is set.

Prior tothe' stitch setting action, the spring member38 occupies apredetermined initial'position represented in Fig. 3. ln this-positionit will be observed that the spring fiiember 38 is located with its headat the rearward limit of its movement near to the rear of the threadcase 8, as viewed by an operator of the illustrative machine.Furthermore, in this same position (Fig. 3) the yieldable paying-Edevice provides a bight in the thread and the spring tension member 28presses the locking thread 24 firmly against the periphery of the threadcase 8 to maintainthe locking thread in a straight position between thepaying-off device and the work. The thread tension due to the spring 28may, in a typical example, be of the order or 1% pounds.

As will be seen from Fig. 5, the thread case 8 is situated within anannular interior of the loop taker 6, the latter being arranged torotate about the thread case 8 and having a beak 42 for entering andcarrying each loop of needle thread 7 over the loop taker and over thelocking thread supply bobbin. The loop of needle thread is drawn downfrom the shuttle to the work and is contracted about the locking thread24 to bring about the setting of each stitch at the point of finalinterlocking engagement between the needle and locking threads withinthe work.

During the stitch setting operation, i.e., as the needle loop exertstension against the locking thread 24 and deflects it toward the work,the paying-off spring 38 yields under the pull of the needle thread awayfrom its initial starting position, represented in Fig. 3 and towardsthat which is represented in Fig. 4. The spring member 38 is thenlocated with its head near the front of the thread case 8. In a typicalexample the spring member 38 may be such as to impart an average tensionwhich is of the order of 12 ounces, it being appreciated that as theneedle thread exerts tension on the locking thread 24 during the stitchsetting operation, the spring member 38 yields lightly and pays out asmuch locking thread as is necessary for the correct setting of thestitch without any withdrawal from the supply bobbin 22.

After the stitch has been set the spring member 38, according to theinvention, is returned positively into its initial predeterminedstarting position, represented in Fig. 3, during which time the head 36of the spring member 38 acts to draw off from the bobbin 22 an amount oflocking thread suflicient to provide a predetermined length for the nextsucceeding stitch. In a typical example, this amount of draw-off fromthe supply bobbin 22 may vary from about 35 of an inch for minimumconditions to about of an inch for maximum conditions.

Referring now to Figs. 5 and 6, the positive return movement of thespring member 38 to its initial position is effected by means of acircular scroll cam 44 in the form of a sleeve which is pressed tightlyinto the annular interior of the loop taker 6 to rotate therewith aroundthe locking thread case 8. The cam 44 at one end is formed with ahelical edge face 45 against which the head 36 of the spring member 38bears and by which face it is thrust progressively from the limitposition represented in Fig. 4, to that which is represented in Fig. 3.When the spring member 38 has thus been returned positively by the cam44 into the position represented in Fig. 3 before each stitch is set bythe take-up, a step 46 formed in the cam frees the head 36 for yieldingmovement during contraction of the needle loop in the setting of thenext stitch. It will be understood, of course, that the contour of thecam 44 and its angular disposition relatively to the loop taker and tothe head 36 will be chosen suitably to ensure that repetitive threaddraw-off movements, alternating with thread pay-off movements, of thespring member 38 occur in the desired times as the loop taker 6 rotates.

To accentuate the locking thread draw and pay-off movements of theyieldable member 38 and to prevent withdrawal of locking thread from thesupply bobbin 22 at other than the proper time, the cam 44 of theillustrated machine is formed on its inner peripheral surface with anenlargement 48 (Figs. 5 and 6) extending through an angle somewhatgreater than as indicated at points a and b in Fig. 5. As the loop takerrotates the enlargement 48 presses against a projection 50 on thetension spring 28 and applies a supplemental clamping pressure to thethread running from the supply in the locking thread case. To apply asupplemental clamping pressure to the thread tension spring at theproper time the relative position of the enlargement 48 and theprojection 50 are such that the supplemental pressure for the threadtension spring occurs while each stitch is being set by the take-up thuscausing the locking thread to be clamped by the tension spring againstthe outer surface of the thread case.

In Fig. 7 is illustrated a modified arrangement of a yieldablepaying-off device. Instead of employing a thread tension spring 28engaging the locking thread 24 between the bobbin and the spring member38, as is shown in Fig. 3, a thread-tension spring 52 which encirclesthe thread case 8 and is retained in position by means of a lockingprojection 54 (Fig. 8) fitting within a keyhole recess formed in a sideWall of the bobbin case 8, has its free end arranged to bear upon thelocking thread 24 as it runs along the periphery of the thread casebetween the eye 30 and the head 36 of the spring member. The lockingthread 24, as it extends from the bobbin passes freely under the spring52 as it emerges from the opening 26, the thread-tension being appliedby reason of the free end only of the spring 52 pressing upon thelocking thread near to the eye 30 between the yieldable member 38 andthe work. In this arrangement, when the setting operation of the stitchoccurs, the stitch is set against a combination of two tensions, namely,one tension due to the spring 52 and the other due to the spring member38. It is to be understood that the movements of the spring member 38 toeffect pay-off and drawoff of the locking thread 24 takes place in amanner similar to that which has been described above in connection withthe arrangement shown in Figs. 2 to 6, inclusive. The scroll cam 44,however, need not be provided with an enlargement 48, since in themodified arrangement shown in Fig. 7 sufiiciently satisfactory resultsmay be obtained without applying any additional clamping pressure to thespring 52 at the stitch setting point of the sewing cycle. Whereextremely accurate stitch formation is required, however, theenlargement 48 is helpful in improving uniformity between the placementof the interlocking threads of successive stitches. Similarly, even inconnection with the arrangement shown in Figs. 2 to 6, the enlargement48 may be dispensed with in cases where sufficiently satisfactoryresults are found to be obtainable without applying the additionalclamping pressure to the tension spring.

While the merit of the illustrated forms of the present invention isderived in a large degree from the eflicient utilization of limitedspace available in the cylindrical side wall of a locking thread case byinsuring a maximum possible movement of a yieldable thread paying-offdevice, the uniformity with which the device acts to pay off thread alsois a contributing factor. Because the thread guiding head 36 of theyielding member 38 also moves from the same initial starting position inpaying-oflf thread, the same yielding resistance is imparted to thethread as each stitch is set in the work with the same tension on thelocking thread. If the head 36 of the yieldable member moved from aposition other than the initial one, the yielding force exerted by themember 38 would be increased correspondingly on account of the springcharacteristics even though all of the thread drawn off by the yieldablemember were not taken up before the head 36 engages its positive stop atthe outer edge of the cutout section 41. In this way the locking threadextending between the thread case and the work not only is maintained instraight position under tension as each needle loop is being drawntoward the work and contracted against the locking thread, but theactual amount of tension in the locking thread is kept from variationfrom one stitch to another so long as the thickness of the work and the7 length of stitch does not change. With changes in thickness of thework and length of stitch corresponding varia tions may occur in thetension on the locking thread but in a manner which is beneficial to theformation of a seam, the tension in the threads of which arecommensurate with the requirements.

The nature and scope of the invention having been indicated and specificembodiments having been described, what is claimed is:

1. A lockstitch sewing machine having stitch-forming devices, includinga hook needle, a thread case containing a supply of locking thread, aloop taker for passing a loop of needle thread about the thread case, atakeup for drawing each needle loopfrom the thread case toward the Work,means for controlling withdrawal of thread from the thread case, and ayieldable member on the thread case for taking up slack thread betweenthe thread case and the work, in combination with means for actuatingthe yieldable member positively in a directionopposite to that of itsyielding movement to return it uniformly to an initial predeterminedstarting position.

2. A lockstitch sewing machine having stitch-forming devices, includinga hook needle, a thread case containing a supply of locking thread, aloop taker for passing a loop of needle thread about the thread case, atake-up for drawing each needle loop from the thread case toward thework, means for controlling withdrawal of thread from the thread case,and a yieldable member on the thread case for taking up slack threadbetween the thread case and the work, in combination with meanscomprising a cam on the loop taker for actuating the yieldable memberpositively in a direction opposite to that of its yielding movement toreturn it uniformly to an initial predeterminedstarting position and todraw off from the supply of locking thread an amount suilicient for thenext succeeding stitch. V

3. A lockstitch sewing machine having stitch-forming devices including ahook needle, a thread case having a cylindrical side wall containing asupply of locking thread, a loop taker for passing a loop of needlethread about the thread case, a take-up for drawing each needle loopfrom the thread case toward the work and a yieldable paying-oft devicemounted on the cylindrical side wall of the thread case for limitedyielding movement to take up slack thread between the thread case andthe work, in combination with means operable positively in a directionopposite to that of the yielding movement of the yieldable device toreturn said device uniformly to an initial predetermined startingposition.

4. A lockstitch sewing machine having stitch-forming devices including ahook needle, a thread case having a cylindrical side wall containing asupply of locking thread, a loop taker for passing a loop of needlethread about the thread case, a take-up for drawing each needle loopfrom the thread case toward the work and a yieldable paying-elf devicemounted on the cylindrical side wall of the thread case for limitedyielding movement to take up slack thread between the thread case andthe work, in combination with means operable positively in a directionopposite to that of the yielding movement of the yieldable device toreturn said device uniformly to an initial predetermined startingposition, comprising a circular scroll cam within the loop taker, thehelical edge face of which bears against the yieldable paying-oildevice.

5. A lockstitch sewing machine having stitch-forming 8 member positivelyin a direction opposite to that of its yielding movementto return ituniformly to an initial predetermined starting position and to draw offfrom the supply of locking thread an amount sufiicient for the nextsucceeding stitch, and means for preventing rotation of the thread casewith the loop taker. I g

6. A lockstitch sewing machine having stitch-forming devices, includinga hook needle, a thread case containing a supply of locking thread, aloop taker for passing a loop of needle thread about the thread case, atake-up for drawing each needle loop from the thread case toward thework, means for controlling withdrawal of thread from the thread case,and a yieldable member onthe thread case for taking up slack threadbetween the thread case and the work, in combination with meanscomprising a cam on the loop taker for actuating the yieldable mermberpositively in a direction opposite to that of its yielding movement toreturn it uniformly to an initial predetermined starting position and todraw off from the sup ply of locking thread an amount sufiicient for thenext succeeding stitch, and means comprising an enlargement on the camengaging the thread controlling means to prevent withdrawal of lockingthread from the supply in the thread case while each stitch is being setby the take-up.

"l. A lockstitch sewing machine having stitch-forming devices,-including a hook needle, a thread case containing a supply of lockingthread, a loop taker for passing a loop of needle thread about thethread case, a take-up for drawing each needle loop from the thread casetoward the work, means for controlling withdrawal of thread from thethread case, and a yieldable member on the thread case for taking upslack thread between the thread case and the work, in combination withmeans comprising a circular scroll cam formed with a helical edge facefor actuating the yieldable member and to enable thread to be paid offas each stitch is set by the take-up, and means comprising anenlargement on the inner surface of the cam acting on the threadcontrolling means to prevent withdrawal of locking thread from thesupply in the' thread case while each stitch is being set by thetake-up;

8. A lockstitch sewing machine having stitch-forming devices, includinga hook needle, a thread case containing a supply of locking thread, aloop taker for passing a loop of needle thread about the thread case, atake-up for drawing each needle loop from the thread case toward thework, means for controlling withdrawal of thread from the thread case,and a yieldable member on the thread case for taking up slack threadbetween the threadcase and the work, in combination with meanscomprising a circular scroll cam formed with a helical edge face foractuating the yieldable member and to enable thread to be payed off aseach stitch is set by the take-up, and means comprising an enlargementon the inner surface of the"- canr acting on the thread controllingmeans to prevent withdrawal of locking thread from the supply in thethread case while each stitch is being set by the take-up,- the threadcontrolling means comprising a flat tension spring engaging the threadbetween the yieldable slack thread take-up member and the work.

9. A lockstitch sewing machine having stitch forniing devices, includinga hook needle, a thread case containing a' supply of locking thread, aloop taker for passing a loop of needle thread about the thread case, atake-up for drawing each needle loop from the thread case toward thework, means for controlling withdrawal of th'rea'd from the thread case,and a yieldable member on the thread case for taking up slack threadbetween the thread case and the work, in combination with means comrising a circular scroll cam formed with a helical edge face foractuating the yieldable member and to enable thread to be payed off aseach stitch is set by the take-up, and means comprising an enlargementon the inner surface of the cam acting on the thread controlling meansto preventwithdrawal of locking thread from the supply in the threadcase While each stitch is being set by the take-up,

the thread controlling means comprising a thread tension spring arrangedto bear on the locking thread between the yieldable slack thread take-upmember and the work.

10. A lockstitch sewing machine having stitch-forming devices includinga hook needle, a thread case having a cylindrical side wall andcontaining a supply of locking thread, a loop taker for passing a loopof needle thread about said thread case, a take-up for taking up eachneedle loop from the thread case and drawing it toward the work, aneedle thread measuring mechanism providing a measured amount of needlethread for each stitch, means for controlling withdrawal of lockingthread from the thread case, and a yieldable member on the thread casefor taking up slack thread between the supply in the thread case and thework, in combination with means for actuating the yieldable memberpositively in a direction opposite to that of its yieldable movement tocause the yieldable member to draw thread from the thread case in anamount equal to that drawn into the work by the needle thread while theprevious stitch is being set.

Ballard June 8, 1915 Haas Feb. 21, 1939

